There are many applications for real-time target sensing and jamming in both Line-of-Sight (LOS) environments and Non-Line-of-Sight (NLOS) environments, including target sensing/jamming behind opaque obstacles such as walls and doors. One such application is sensing a drone or another type of unmanned aerial vehicle (UAV) as it enters a protected area, to facilitate monitoring the UAV and controlling the UAV's activities. Another application is monitoring occupant motion by home automation systems, for example, to enable energy conservation measures and/or home security measures. In both of these types of applications, and in others, there is a need for systems and methods that can quickly beamform an electromagnetic signal based on processing the space, time, and frequency data embedded in the backscattered/reflected radiation.
Through-the-wall imaging with Synthetic Aperture Radar (SAR) may be effective in both military and commercial applications to identify, monitor, and track objects. SAR sensing may employ unlicensed and/or ultra-wideband (UWB) frequencies, as well as chirp and
Orthogonal Frequency Division Multiplexing (OFDM) waveforms. A disadvantage of SAR systems in these applications may be SAR's typical complexity, long processing times, and high cost of infrastructure. One of the challenges of existing SAR technologies is that during the long space, time, and frequency signal processing duration of the backscattered radiation, the target may move, making the beamformed signal no longer sufficiently effective.
As the ubiquity of small UAVs increases, scalable low cost solutions to detect them, track them, and jam their communication links are gaining importance. Detection of UAVs with small radar cross sections (RCS) has often proven to be a challenge even with powerful and expensive phased arrays, including radar panels that require large platforms such truck-mounted radar panels. To detect weak RCS targets, scanning with a focused beam to obtain sufficient signal-to-noise ratio (SNR) may be important, resulting in a brute force raster scanning/panel rotation hemisphere searches of relatively long durations (e.g., tens of seconds), with multiple radar platforms needed in some cases to cover a large area. Another disadvantage of such conventional radar systems is that they have strong radar emissions that can reveal their locations, and hence the radar systems may be easily targeted for suppression. Furthermore, with the advent of sophisticated UAVs made with radar-absorbent materials, operation in X-Ku band frequencies may not present a viable solution, particularly for low-cost scalable radios. Therefore, scaling to low frequencies for resonance detection is not always feasible as the radar aperture size scales linearly with wavelength, resulting in unmanageably large radar panel sizes.
Additionally, widely-spaced sparse apertures for long-range detection are often not feasible, because they may require robust phase and frequency synchronization across all nodes, as well as intensive computations to calculate the beamforming weights.
A need in the art exists for improved techniques for overcoming these difficulties. A need in the art also exists for apparatus and articles of manufacture using such techniques to overcome these difficulties.